Sorry for wrong sample...
The correct one should look like:
web_reg_save_param_regexp(
"ParamName=CorrelationParameter_2",
//"RegExp=idpersona=(.*?)&primeraopcion",
"RegExp=(idpersona|id_alumno)=(.*?)&primeraopcion",
"Group=2",
SEARCH_FILTERS,
"Scope=Headers",
"IgnoreRedirections=No",
"RequestUrl=*/index.php*",
LAST);
The first capture group contains the alternatives (idpersona or id_alumno) , while the second one takes the desired value.
Thanks,
Leonid.